1. Field of the Invention
This invention relates to a method and apparatus for fabricating workpieces of metal or other materials. More specifically, the invention embodies dual work members in alignment with each other and with a movable anvil such that an equalization of forces may be achieved during a two-phase sequential fabricating operation to reduce distortion on separate aligned portions of a workpiece. This invention may be used in welding, riveting, punching, piercing, pressing, stamping, etc., wherever there is an application of force to two essentially aligned sections of a workpiece.
2. The Prior Art
Various prior art patents have disclosed different apparatus for achieving essentially equalized pressure on opposite faces of a workpiece during a fabricating operation. Such patents include U.S. Pat. Nos. 3,270,604, 3,299,247, 3,396,260, 3,008,032, 3,008,034, and 3,136,879, all incorporated by reference. As recognized particularly in U.S. Pat. No. 3,270,604, it is desirable to equalize the force on the workpiece in order to minimize or eliminate workpiece distortion.
For the most part, the prior art has not provided an apparatus or method for achieving a dual fabrication operation on two essentially parallel sections of a workpiece. Only one of the above-enumerated patents U.S. Pat. No. 3,270,604, discloses such an apparatus and method. However, the apparatus disclosed in that patent exhibits certain drawbacks. For example, in the apparatus of U.S. Pat. No. 3,270,604 the hydraulic units are positioned at each end of the unit with the anvil being in essentially the center. While the overall structure has provided significant advances in the art, the general arrangement necessarily can not perform certain desired operations. For example, the smaller vehicles now include parts which can not be fabricated in the prior arrangement; and the prior arrangement could not be utilized with another such apparatus so that the anvils could receive workpieces which require four aligned fabrications. As a result, manual labor has been required to position and then reposition the workpieces, resulting in longer cycle times and greater fabrication expenses.
Accordingly, the prior art has evidenced certain shortcomings and disadvantages, even as related to fabrication operations performed in alignment on parallel sections of a workpiece.